1. Field of the Invention
This invention relates to a self-managing storage station employing variable length fields that can be nested to any level and more particularly to such a station under microprocessor control so that it may be employed either as a stand-alone station or in a network of one or more such stations.
2. Description of the Prior Art
Prior art storage systems have evolved as an array of identical storage cells which were arranged in a rigid manner to accommodate parallel processing. Parallel data transfer in data processing systems was employed to compensate for the relatively slow speeds of the switching elements employed in the system. Parallel data transfer, in turn, required a fixed width for data or information segments which greatly inhibited the accommodation of variable length fields and nested data structures. As a result, elaborate operating systems and other program mechanisms were created to handle the various data structures and to provide security and protection features. Some of these program mechanisms have been implemented in circuitry with some success. However, the result was still cumbersome.
Improvements in circuit components, particularly in integrated circuits, have allowed for the decentralization of the various functions in various systems and their networks. Large scale integrated circuit technology requires regularity and dedication of specialized or complex functions to circuit chips. Distribution of functions throughout a number of similar or identical integrated circuit chips can accommodate serial data transfer without an undue reduction of throughput in the system. Serial data transfer both accommodates and may be implemented in a number of new storage devices such as charge couple devices (CCD), magnetic bubble memories, and also by improvements in magnetic disk memories which have greatly enhanced access times for storage capabilities. A self-managing variable field storage system for handling nested data structures is described in the Barton and Hodgman U.S. Pat. No. 4,027,288, which system overcomes many of the above-described disadvantages. This system provides all of the following functions:
Retention of variable-length strings of symbols, up to an implementation-defined maximum;
automatic allocation and reclamation of unused storage space as strings of information increase or decrease in size;
explicit representation of the beginning and end of strings and the decomposition of strings into substrings;
access of storage strings by means of symbolic names;
storage of strings of information in ordered sets and access to them according to their order;
permission or prohibition of access to strings of information depending upon the identities of the sources of creation of those strings and which sources try to access them;
provision of optional internal representations of strings which optimize access speed by taking advantage of the physical structure of various storage media; and
transmission of strings of information of variable lengths between the storage mechanism and external agencies according to a fixed discipline.
It is, then, an object of the present invention to provide a self-managing storage station that can provide many information-handling functions without the requirement of control by a central processing element.
It is another object of the present invention to provide a self-managing storage mechanism that can accommodate variable-length data segments that may be nested to any level.
It is still a further object of the present invention to provide a self-managing storage station that automatically allocates and reclaims unused storage space.